Ongoing cell culture studies of genetic and metabolic contributions of articular chondrocytes to degenerative joint diseases and disturbed skeletal growth will be carried forward. These include a comparison of the in vitro behavior of lapine articular and growth plate chondrocytes, with particular emphasis on the response to a pituitary growth factor; experimental siderosis as a model of hemophilic arthropathy; and immunohistochemial studies of the collagens synthesized by the chondrocytes.